I feel that texture determines drag more than standard silicone vs Vixskin. Given that Vixskin is silicone it's an interesting question, but since Vixskin always has a velvety or skin like texture and standard silicone can have a very smooth almost glassy texture like the feeldoe line I say Vixskin.

The amount of drag silicone has varies quite a bit depending on things like texture and firmness. Different companies also tend to have their silicone sit on one side of the fence or the other. Whether or not VixSkin (which, incidentally, is silicone) has more or less drag than other silicone basically depends on which toy you're comparing it to. However, taken on its own, VixSkin is fairly draggy without lube.

The shinier the surface of the silicone the less drag it has (because it's smoother). Vixskin tends towards the shiner side of the spectrum, but it's not as slick as the super-smooth finish on some Tantus toys.

Vixskin is just another type of silicone, but it sounds like the surface on it is lower-drag? I think the surface texture is the most important factor for drag. Like wind resistance for your orifices! (oh that sounds bad...)

VixSkin is silicone, only it's a dual density silicone. That said, Vixskin is going to give more like moving skin up or down the shaft of a real penis. So, in a sense that may be considered drag. But, put some good water base lube on that dildo, or penis, and it may be considered a wonderful sensation by some.